This striking plume of yellow is the fluorescing tail feathers of a male emperor bird-of-paradise (Paradisaea guilielmi). Birds-of-paradise are known for their bright colours and courtship displays. Now, it turns out that many species also fluoresce 鈥� absorbing light and re-emitting it at lower-energy wavelengths. Fluorescent patches are found in body parts used during courtship, like tail feathers and bills.
